With the rapid developments in very large-scale integration (VLSI) technology, design and computer-aided design (CAD) techniques, at both the chip and package level, the operating frequencies are fast reaching the vicinity of gigahertz and switching times are getting to the subnanosecond levels. The ever increasing quest for high-speed applications is placing higher demands on interconnect performance and highlighted the previously negligible effects of interconnects such as ringing, signal delay, distortion, reflections, and crosstalk. In this review paper various high-speed interconnect effects are briefly discussed. In addition, recent advances in transmission line macromodeling techniques are presented. Also, simulation of high-speed interconnects using model-reduction-based algorithms is discussed in detail.

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Simulation of high-speed interconnects

The current induced on an infinite multiple conductor transmission line located above a lossy homogeneous medium due to a transient plane wave is discussed. An exact solution is formulated in the frequency domain using a spatial transform technique. The widely utilized quasi-TEM approximation is derived directly from the exact solution with emphasis on the physical consequences of the assumptions made. Both frequency domain and time domain numerical results are presented for typical transmission structures and documented electromagnetic pulse (EMP) excitations. Comparison of the quasi-TEM approximation to the exact solution is made in order to study the validity of its application in EMP coupling problems. The modeling of the EMP source as an incident plane wave is examined by comparing the induced current due to a dipole source with its steepest-descent contribution. >

Plane wave coupling to multiple conductor transmission lines above a lossy earth

There have been reports in the media and claims in the courts that radiofrequency (RF) emissions from mobile phones are a cause of cancer, and there have been numerous public objections to the siting of mobile phone base antennas because of a fear of cancer. This review summarizes the current state of evidence concerning whether the RF energy used for wireless communication might be carcinogenic. Relevant studies were identified by searching MedLine with a combination of exposure and endpoint terms. This was supplemented by a review of the over 1700 citations assembled by the Institute of Electrical and Electronics Engineers (IEEE) International Committee on Electromagnetic Safety as part of their updating of the IEEE C95.1 RF energy safety guidelines. Where there were multiple studies, preference was given to recent reports, to positive reports of effects and to attempts to confirm such positive reports. Biophysical considerations indicate that there is little theoretical basis for anticipating that RF energy would have significant biological effects at the power levels used by modern mobile phones and their base station antennas. The epidemiological evidence for a causal association between cancer and RF energy is weak and limited. Animal studies have provided no consistent evidence that exposure to RF energy at non-thermal intensities causes or promotes cancer. Extensive in vitro studies have found no consistent evidence of genotoxic potential, but in vitro studies assessing the epigenetic potential of RF energy are limited. Overall, a weight-of-evidence evaluation shows that the current evidence for a causal association between cancer and exposure to RF energy is weak and unconvincing. However, the existing epidemiology is limited and the possibility of epigenetic effects has not been thoroughly evaluated, so that additional research in those areas will be required for a more thorough assessment of the possibility of a causal connection between cancer and the RF energy from mobile telecommunications.

Mobile phones, mobile phone base stations and cancer: a review

http://www.wifiinschools.org.uk/resources/Ruediger+2009.pdf

Genotoxic effects of radiofrequency electromagnetic fields.

There has been growing concern about the possibility of adverse health effects resulting from exposure to radiofrequency radiations (RFR), such as those emitted by wireless communication devices. Since the introduction of mobile phones many studies have been conducted regarding alleged health effects but there is still some uncertainty and no definitive conclusions have been reached so far. Although thermal effects are well understood they are not of great concern as they are unlikely to result from the typical low-level RFR exposures. Concern rests essentially with the possibility that RFR-exposure may induce non-thermal and/or long-term health effects such as an increased cancer risk. Consequently, possible genetic effects have often been studied but with mixed results. In this paper we review the data on alleged RFR-induced genetic effects from in vitro and in vivo investigations as well as from human cytogenetic biomonitoring surveys. Attention is also paid to combined exposures of RFR with chemical or physical agents. Again, however, no entirely consistent picture emerges. Many of the positive studies may well be due to thermal exposures, but a few studies suggest that biological effects can be seen at low levels of exposure. Overall, however, the evidence for low-level genotoxic effects is very weak.

In vitro and in vivo genotoxicity of radiofrequency fields

The coupling of external electromagnetic waves to transmission lines is developed using a circuit-analysis concept. The validity of forcing terms of line equations reported in the literature is confirmed by experimental results of a wire model that is installed above a ?perfectly? conducting ground plane and excited by plane waves of parallel and perpendicular polarizations. Equivalent-circuit representations are derived from solutions of the equations. These are versatile expressions for prediction of coupling of external waves to various types of lines. Coupling, externally excited transmission line, line equations, forcing terms.

Circuit-Concept Approach to Externally Excited Transmission Lines

A possible mutagenic effect of 2.45 GHz radiofrequency exposure was examined using lacZ-transgenic Muta mice. Pregnant animals were exposed intermittently at a whole-body averaged specific absorption rate of 0.71 W/kg (10 seconds on, 50 seconds off which is 4.3 W/kg during the 10 seconds exposure). Offspring that were exposed in utero for 16 hours a day, from the embryonic age of 0 to 15 days, were examined at 10 weeks of age. To minimize thermal effects, the exposure was given in repeated bursts of 10 seconds of exposure followed by 50 seconds of no exposure. Mutation frequencies at the lacZ gene in spleen, liver, brain, and testis were similar to those observed in non-exposed mice. Quality of mutation assessed by sequencing the nucleotides of mutant DNAs revealed no appreciable difference between exposed and non-exposed samples. The data suggest that the level of radiofrequency exposure studied is not mutagenic when administered in utero in short repeated bursts.

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Absence of mutagenic effects of 2.45 GHz radiofrequency exposure in spleen, liver, brain, and testis of lacZ-transgenic mouse exposed in utero.

The radiation phenomenon from a transmission line of finite length is described. Based on the hypothesis of reciprocity between the coupling of an external wave to a transmission line and the radiation from a transmission line, a set of models for both phenomena is implemented using a six-terminal network. The goal is to find out what current is induced in each terminal load of the network. The radiation characteristics of finite-length lines such as radiation fields, radiation power-density, and radiation coefficients are considered. Experiments using both straight lines and bent lines have been performed to validate the theory. >

Analysis of radiation characteristics of a finite-length transmission line using a circuit-concept approach

Equivalent transformations, which were recently derived for mixed lumped and distributed circuits, may be extended to circuits consisting of lumped reactance, resistors, and Iossy transmission lines. It is shown that circuits consisting of a cascade connection of lumped element sections and Iossy uniform transmission lines are equivalent to circuits consisting of a cascade connection of lossy nonuniform transmission lines, lumped elements, and ideal transformers. Furthermore, by considering the limiting case of these transformations, equivalent transformations for circuits consisting of a cascade connection of lumped reactance, resistors, and nonuniform transmission lines are obtained. Exact equivalent circuits of Iossy even-order binomial form transmission lines are derived from these equivalent transformations.

Equivalent Representations of Lossy Nonuniform Transmission Lines

New nonuniform transmission-linematching networks for a class of lumped complex loads are presented. A parabolic (or reciprocal parabolic) tapered transmission line, whose exact equivalent circuit is represented by a mixed lumped and distributed circuit, can transform the lumped series RC (or parallel RL) loads into different lumped impedances which are more convenient than the original load impedances for ordinary matching network design. Simple design procedures are described and useful design charts are given. Also, numerical examples are shown including experimental verification.

Risaburo Sato

Papers

Circuit-Concept Approach to Externally Excited Transmission Lines

Absence of mutagenic effects of 2.45 GHz radiofrequency exposure in spleen, liver, brain, and testis of lacZ-transgenic mouse exposed in utero.

Analysis of radiation characteristics of a finite-length transmission line using a circuit-concept approach

Equivalent Representations of Lossy Nonuniform Transmission Lines

Impedance Transformation and Matching for Lumped Complex Load with Nonuniform Transmission Line